mrdutvam kathinatvam ca

 saityam usnatvam eva ca

etat sparsasya sparsatvam

 tan-matratvam nabhasvatah

 

Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 

 

Softness and hardness and cold and heat are the distinguishing attributes of touch, which is characterized as the subtle form of air.

 

Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 

 

Tangibility is the proof of form. In actuality, objects are perceived in two different ways. They are either soft or hard, cold or hot, etc. This tangible action of the tactile sense is the result of the evolution of air, which is produced from the sky.